Baby's body systems are starting to get the hang of things. But it is still hard work keeping baby healthy. In this volume baby gets a bump on the forehead, a vaccination, RS virus, is constipated, and chokes. Red Blood Cell also meets White Blood Cell and Killer T for the first time, and talks to F about how he's been treating her.
Just as educational as the original series. If I were still teaching Biology I'd totally include this series and the original in my curriculum. It teaches the parts of the very complicated immune system so memorably, and also includes great bits on other body systems. These are super educational and it doesn't feel like you're getting educated. These baby ones are kept more middle grade appropriate than the original with no swearing (heck is the worst thing said) and the takedowns of bad invaders are less bloody.
Notes on content: No language issues. No sexual content. Some viruses are destroyed in a fight, but it is more implied than shown. The baby faces some potentially serious threats, but is ok.